Indoor Liquid/Suction Heat Exchanger

ABSTRACT

Systems and methods are disclosed that include providing an air conditioning (A/C) system having an indoor unit with a Liquid/Suction Heat Exchanger (LSHX) coupled between an outdoor heat exchanger of an outdoor unit and an indoor metering device on a so-called “liquid” line and coupled between an indoor heat exchanger and a compressor of the outdoor unit on a so-called “vapor” line. The LSHX is configured to increase the efficiency of the A/C system by increasing the amount of subcooling in the refrigerant on the liquid line of the LSHX and increasing the amount of superheat in the refrigerant on the vapor line of the LSHX.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 62/110,496 filed on Jan. 31, 2015 by Stephen Stewart Hancock, and entitled “Indoor Liquid/Suction Heat Exchanger,” the disclosure of which is hereby incorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Air conditioning (A/C) systems may generally be used in residential and/or commercial areas cooling to create comfortable temperatures inside those areas. Some A/C systems may generally be capable of cooling a comfort zone by transferring heat from a comfort zone to an ambient zone using a refrigeration cycle. To facilitate efficient and effective heat transfer in the heat pump system, refrigerant temperature management remains a critical part of the A/C system design.

SUMMARY

In some embodiments of the disclosure, an indoor unit of an air conditioning (A/C) system is disclosed as comprising a liquid/suction heat exchanger (LSHX) and a superheat sensor configured to monitor the amount of superheat in refrigerant exiting the LSHX.

In other embodiments of the disclosure, an air conditioning (A/C) system is disclosed as comprising: an outdoor unit; and an indoor unit, comprising: a liquid/suction heat exchanger (LSHX); and a superheat sensor configured to monitor the amount of superheat in refrigerant exiting the LSHX.

In yet other embodiments of the disclosure, a method of operating an air conditioning (A/C) system is disclosed as comprising: providing an A/C system comprising an outdoor unit and an indoor unit comprising an indoor metering device and a liquid/suction heat exchanger (LSHX); monitoring the amount of superheat in refrigerant exiting the LSHX; and adjusting a position of the indoor metering device to control the amount of superheat in the refrigerant exiting the LSHX.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description:

FIG. 1 is a schematic diagram of an air conditioning (A/C) system according to an embodiment of the disclosure;

FIG. 2 is a schematic diagram of an air conditioning (A/C) system according to another embodiment of the disclosure;

FIG. 3 is a flowchart of a method of operating an air conditioning (A/C) system according to an embodiment of the disclosure; and

FIG. 4 is a schematic diagram of a general-purpose processor according to an embodiment of the disclosure.

DETAILED DESCRIPTION

Referring now to FIG. 1, a schematic diagram of an air conditioning (A/C) system 100 is shown according to an embodiment of the disclosure. Most generally, A/C system 100 may be selectively operated to implement a closed thermodynamic refrigeration cycle to provide a cooling functionality (hereinafter, “cooling mode”). The A/C system 100 generally comprises an indoor unit 102, an outdoor unit 104, and a system controller 106 that may generally control operation of the indoor unit 102 and/or the outdoor unit 104.

Indoor unit 102 generally comprises an indoor heat exchanger 108, an indoor fan 110, an indoor metering device 112, and an indoor controller 124. The indoor heat exchanger 108 may generally be configured to promote heat exchange between refrigerant carried within internal tubing of the indoor heat exchanger 108 and an airflow that may contact the indoor heat exchanger 108 but that is segregated from the refrigerant. In some embodiments, indoor heat exchanger 108 may comprise a plate-fin heat exchanger. However, in other embodiments, indoor heat exchanger 108 may comprise a spine fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger.

The indoor fan 110 may generally comprise a centrifugal blower comprising a blower housing, a blower impeller at least partially disposed within the blower housing, and a blower motor configured to selectively rotate the blower impeller. The indoor fan 110 may generally be configured to provide airflow through the indoor unit 102 and/or the indoor heat exchanger 108 to promote heat transfer between the airflow and a refrigerant flowing through the indoor heat exchanger 108. The indoor fan 110 may also be configured to deliver temperature-conditioned air from the indoor unit 102 to one or more areas and/or zones of a climate controlled structure. The indoor fan 110 may generally comprise a centrifugal, mixed-flow fan and/or any other suitable type of fan. The indoor fan 110 may generally be configured as a modulating and/or variable speed fan capable of being operated at many speeds over one or more ranges of speeds. In other embodiments, the indoor fan 110 may be configured as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different ones of multiple electromagnetic windings of a motor of the indoor fan 110. In yet other embodiments, however, the indoor fan 110 may be a single speed fan.

The indoor metering device 112 may generally comprise an active expansion valve. More specifically, the indoor metering device 112 may comprise an electronically-controlled motor-driven electronic expansion valve (EEV). In some embodiments, however, the indoor metering device 112 may comprise a thermostatic expansion valve. In some embodiments, while the indoor metering device 112 may be configured to meter the volume and/or flow rate of refrigerant through the indoor metering device 112, the indoor metering device 112 may also comprise and/or be associated with a refrigerant check valve and/or refrigerant bypass configuration when the direction of refrigerant flow through the indoor metering device 112 is such that the indoor metering device 112 is not intended to meter or otherwise substantially restrict flow of the refrigerant through the indoor metering device 112.

Outdoor unit 104 generally comprises an outdoor heat exchanger 114, a compressor 116, an outdoor fan 118, and an outdoor controller 126. In some embodiments, the outdoor unit 104 may also comprise a plurality of temperature sensors for measuring the temperature of the outdoor heat exchanger 114, the compressor 116, and/or the outdoor ambient temperature. The outdoor heat exchanger 114 may generally be configured to promote heat transfer between a refrigerant carried within internal passages of the outdoor heat exchanger 114 and an airflow that contacts the outdoor heat exchanger 114 but that is segregated from the refrigerant. In some embodiments, outdoor heat exchanger 114 may comprise a plate-fin heat exchanger. However, in other embodiments, outdoor heat exchanger 114 may comprise a spine-fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger.

The compressor 116 may generally comprise a variable speed scroll-type compressor that may generally be configured to selectively pump refrigerant at a plurality of mass flow rates through the indoor unit 102, the outdoor unit 104, and/or between the indoor unit 102 and the outdoor unit 104. In some embodiments, the compressor 116 may comprise a rotary type compressor configured to selectively pump refrigerant at a plurality of mass flow rates. In alternative embodiments, however, the compressor 116 may comprise a modulating compressor that is capable of operation over a plurality of speed ranges, a reciprocating-type compressor, a single speed compressor, and/or any other suitable refrigerant compressor and/or refrigerant pump.

The outdoor fan 118 may generally comprise an axial fan comprising a fan blade assembly and fan motor configured to selectively rotate the fan blade assembly. The outdoor fan 118 may generally be configured to provide airflow through the outdoor unit 104 and/or the outdoor heat exchanger 114 to promote heat transfer between the airflow and a refrigerant flowing through the indoor heat exchanger 108. The outdoor fan 118 may generally be configured as a modulating and/or variable speed fan capable of being operated at a plurality of speeds over a plurality of speed ranges. In other embodiments, the outdoor fan 118 may comprise a mixed-flow fan, a centrifugal blower, and/or any other suitable type of fan and/or blower, such as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different multiple electromagnetic windings of a motor of the outdoor fan 118. In yet other embodiments, the outdoor fan 118 may be a single speed fan. Further, in other embodiments, however, the outdoor fan 118 may comprise a mixed-flow fan, a centrifugal blower, and/or any other suitable type of fan and/or blower.

The system controller 106 may generally be configured to selectively communicate with an indoor controller 124 of the indoor unit 102, an outdoor controller 126 of the outdoor unit 104 and/or other components of the A/C system 100. In some embodiments, the system controller 106 may be configured to control operation of the indoor unit 102 and/or the outdoor unit 104. In some embodiments, the system controller 106 may be configured to monitor and/or communicate with a plurality of temperature sensors associated with components of the indoor unit 102, the outdoor unit 104, and/or the ambient outdoor temperature. Additionally, in some embodiments, the system controller 106 may comprise a temperature sensor and/or may further be configured to control heating and/or cooling of zones associated with the A/C system 100. In other embodiments, however, the system controller 106 may be configured as a thermostat for controlling the supply of conditioned air to zones associated with the A/C system 100.

The system controller 106 may also generally comprise a touchscreen interface for displaying information and for receiving user inputs. The system controller 106 may display information related to the operation of the A/C system 100 and may receive user inputs related to operation of the A/C system 100. However, the system controller 106 may further be operable to display information and receive user inputs tangentially and/or unrelated to operation of the A/C system 100. In some embodiments, however, the system controller 106 may not comprise a display and may derive all information from inputs from remote sensors and remote configuration tools.

The indoor controller 124 may be carried by the indoor unit 102 and may generally be configured to receive information inputs, transmit information outputs, and/or otherwise communicate with the system controller 106, the outdoor controller 126, and/or any other device via any suitable medium of communication. In some embodiments, the indoor controller 124 may be configured to receive information related to a speed of the indoor fan 110, transmit a control output to an electric heat relay, transmit information regarding an indoor fan 110 volumetric flow-rate, and communicate with an indoor EEV controller 128 configured to control operation of the indoor metering device 112. In some embodiments, the indoor controller 124 may be configured to communicate with an indoor fan controller and/or otherwise affect control over operation of the indoor fan 110.

The indoor EEV controller 128 may be configured to receive information regarding temperatures and/or pressures of the refrigerant in the indoor unit 102. More specifically, the indoor EEV controller 128 may be configured to receive information regarding temperatures and pressures of refrigerant entering, exiting, and/or within the indoor heat exchanger 108. Further, the indoor EEV controller 128 may be configured to communicate with the indoor metering device 112 and/or otherwise affect control over the indoor metering device 112.

The outdoor controller 126 may be carried by the outdoor unit 104 and may be configured to receive information inputs, transmit information outputs, and/or otherwise communicate with the system controller 106, the indoor controller 124, and/or any other device via any suitable medium of communication. In some embodiments, the outdoor controller 126 may be configured to receive information related to an ambient temperature associated with the outdoor unit 104, information related to a temperature of the outdoor heat exchanger 114, and/or information related to refrigerant temperatures and/or pressures of refrigerant entering, exiting, and/or within the outdoor heat exchanger 114 and/or the compressor 116. In some embodiments, the outdoor controller 126 may be configured to transmit information related to monitoring, communicating with, and/or otherwise affecting control over the compressor 116, the outdoor fan 118, a relay associated with adjusting and/or monitoring a refrigerant charge of the A/C system 100, and/or a position of the indoor metering device 112. The outdoor controller 126 may further be configured to communicate with and/or control a compressor drive controller that is configured to electrically power and/or control the compressor 116.

The A/C system 100 is shown configured for operating in the cooling mode in which heat is absorbed by refrigerant at the indoor heat exchanger 108 and heat is rejected from the refrigerant at the outdoor heat exchanger 114. In some embodiments, the compressor 116 may be operated to compress refrigerant and pump the relatively high temperature and high pressure compressed refrigerant from the compressor 116 to the outdoor heat exchanger 114. As the refrigerant is passed through the outdoor heat exchanger 114, the outdoor fan 118 may be operated to move air into contact with the outdoor heat exchanger 114, thereby transferring heat from the refrigerant to the air surrounding the outdoor heat exchanger 114 (condenser in cooling mode). The refrigerant may primarily comprise liquid phase refrigerant and the refrigerant may flow from the outdoor heat exchanger 114 to the indoor metering device 112. The indoor metering device 112 may meter passage of the refrigerant through the indoor metering device 112 so that the refrigerant downstream of the indoor metering device 112 is at a lower pressure than the refrigerant upstream of the indoor metering device 112. The pressure differential across the indoor metering device 112 allows the refrigerant downstream of the indoor metering device 112 to expand and/or at least partially convert to a two-phase (vapor and gas) mixture. The two phase refrigerant may enter the indoor heat exchanger 108 (evaporator in cooling mode). As the refrigerant is passed through the indoor heat exchanger 108, the indoor fan 110 may be operated to move air into contact with the indoor heat exchanger 108, thereby transferring heat to the refrigerant from the air surrounding the indoor heat exchanger 108, and causing evaporation of the liquid portion of the two phase mixture. The refrigerant may thereafter re-enter the compressor 116.

Referring now to FIG. 2, an A/C system 200 is shown according to another embodiment of the disclosure. A/C system 200 may generally be substantially similar to A/C system 100 and comprise outdoor unit 104 and system controller 106. A/C system 200 also comprises an indoor unit 202 that is substantially similar to indoor unit 102. However, indoor unit 202 comprises a Liquid/Suction Heat Exchanger (LSHX) 230 and a superheat sensor 240. Generally, the LSHX 230 may be coupled between the outdoor heat exchanger 114 and the indoor metering device 112 on a so-called “liquid” line. Additionally, the LSHX 230 may be coupled between the indoor heat exchanger 108 and the compressor 116 on a so-called “vapor” line. The LSHX 230 may generally be configured to increase the efficiency of the A/C system 200 by providing optimal system subcooling and/or superheat in the refrigerant of the A/C system 200 as compared to A/C system 100 that does not include an LSHX 230 and must accomplish said subcooling and superheat in the outdoor and indoor heat exchangers, respectively. Subcooling refers to the number of degrees that liquid refrigerant is below the refrigerant saturation temperature (when condenses to a liquid), while superheat refers to the number of degrees that vapor refrigerant is above the refrigerant saturation temperature.

The superheat sensor 240 may generally be disposed on the so-called suction line at a location downstream from the LSHX 230 and configured to measure the temperature and/or the pressure of the refrigerant exiting the LSHX 230. In alternative embodiments, the superheat sensor 240 may be disposed upstream of the LSHX 230 between the LSHX 230 and the indoor heat exchanger 108 and configured to measure and/or monitor the temperature and/or the pressure of the refrigerant entering the LSHX 230. Generally, the indoor controller 124 may be configured to monitor the temperature of the vapor refrigerant exiting the LSHX 230 via the superheat sensor 240 and communicate with the indoor EEV controller 128 to control the position of and/or operation of the indoor metering device 112. By monitoring the superheat sensor 240 and controlling the indoor metering device 112, the indoor controller 124 may control the amount of superheat in the refrigerant exiting the indoor heat exchanger 108 and/or exiting the LSHX 230. Alternatively, the temperature of the vapor refrigerant leaving the LSHX 230 could be monitored with a sensing bulb of a thermostatic expansion valve, the superheat thereby being controlled by the thermostatic expansion valve.

When the A/C system 200 is operated in the cooling mode, the LSHX 230 may receive subcooled refrigerant from the outdoor heat exchanger 114. Generally, the amount of subcooling in the refrigerant entering the LSHX 230 may be at least about 1 degree Fahrenheit. However, in other embodiments, the amount of subcooling in the refrigerant received by the LSHX 230 may be at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, and/or at least about 10 degrees Fahrenheit. The subcooled refrigerant may pass through the LSHX 230 and be further cooled within the LSHX 230. Accordingly, the LSHX 230 may be configured to further increase the amount of subcooling within the refrigerant passing though the LSHX 230. In some embodiments, the LSHX 230 may increase the amount of subcooling to at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, at least about 10 degrees Fahrenheit, and/or at least about 12 degrees Fahrenheit. Because some of the subcooling is performed by the LSHX 230, the outdoor heat exchanger 114 may transfer heat more efficiently and/or effectively, thereby increasing the efficiency of the A/C system 200.

The LSHX 230 receives refrigerant that exits the indoor heat exchanger 108 after having passed through the indoor heat exchanger 108. In some embodiments, refrigerant leaving the indoor heat exchanger 108 may be superheated by at least about 1 degree Fahrenheit. However, in other embodiments, the refrigerant leaving the indoor heat exchanger 108 may comprise a superheat of at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, and/or at least about 10 degrees Fahrenheit. The superheated refrigerant may pass through the LSHX 230 and be further superheated within the LSHX 230. Accordingly, the LSHX 230 may be configured to further increase the amount of superheat within the refrigerant passing though the LSHX 230. In some embodiments, the LSHX 230 may increase the amount of superheat to at least about 2 degrees Fahrenheit, at least about 3 degrees Fahrenheit, at least about 5 degrees Fahrenheit, at least about 7 degrees Fahrenheit, at least about 10 degrees Fahrenheit, and/or at least about 12 degrees Fahrenheit. Because the majority of the superheat is performed by the LSHX 230, the indoor heat exchanger 108 may transfer heat more efficiently and/or effectively, thereby increasing the efficiency of the A/C system 200.

After the refrigerant is further superheated within the LSHX 230, the superheated refrigerant may exit the LSHX 230. The superheat sensor 240 may continuously monitor the temperature and/or the pressure of the superheated refrigerant exiting the LSHX 230. Generally, the position of the indoor metering device 112 may be controlled by the indoor EEV controller 128 in response to the superheat sensor 240 communicating the temperature and/or pressure of the superheated refrigerant exiting the LSHX 230 to the indoor controller 124. To increase the superheat in the refrigerant exiting the LSHX 230, the indoor metering device 112 may be adjusted to reduce the pressure of the refrigerant exiting the indoor metering device 112 and entering the indoor heat exchanger 108. Alternatively, to reduce the superheat in the refrigerant exiting the LSHX 230, the indoor metering device 112 may be adjusted to increase the pressure of the refrigerant exiting the indoor metering device 112 and entering the indoor heat exchanger 108. Accordingly, the position of the indoor metering device 112 may be continuously adjusted to maintain a specified and/or predetermined amount of superheat in the refrigerant leaving the LSHX 230.

From the LSHX 230, superheated refrigerant may then exit the indoor unit 202 and enter the outdoor unit 104, where it may then pass to the compressor 116. Since the refrigerant entering the compressor 116 is superheated, substantially no liquid-phase refrigerant may pass to the compressor 116. As such, substantially all of the refrigerant that passes to the compressor 116 may be in a superheated, vapor phase. Because liquid refrigerant may cause damage to the compressor 116, the LSHX 230 prevents liquid-phase refrigerant from entering the compressor 116 by superheating the refrigerant that passes through the LSHX 230.

Additionally, after refrigerant has been compressed by the compressor 116 and passed through the outdoor heat exchanger 114, the refrigerant may be passed from the outdoor heat exchanger 114 to the LSHX 230 through liquid line 250. In some embodiments, liquid line 250 may be about 30 feet long. Because much of the subcooling is performed by the LSHX 230 as opposed to the outdoor heat exchanger 114 as in A/C system 100, refrigerant in the liquid line 250 may be about 5 to about 6 degrees Fahrenheit warmer than in a liquid line of A/C system 100. Accordingly, the liquid line 250 may promote heat transfer between the refrigerant in the liquid line 250 and the surrounding ambient environment, thereby further increasing the efficiency of the AC system 200.

The LSHX 230 may generally be configured to increase the efficiency of the A/C system 200 by reducing the amount of subcooling in the refrigerant leaving the outdoor heat exchanger 118 (condenser) and reducing the amount of superheat in the refrigerant leaving the indoor heat exchanger 114 (evaporator). In order to effectively boost the efficiency of the A/C system 200, refrigerant entering the LSHX 230 in the liquid line must always be at least slightly subcooled, and refrigerant entering the LSHX 230 on the vapor line must always be at least slightly superheated. If two-phase refrigerant enters either side of the LSHX 230, excessive heat exchange may occur in LSHX 230 and degrade efficiency of the LSHX 230 and/or the A/C system 200. Additionally, two-phase refrigerant entering the LSHX 230 may also cause the indoor metering device 112 to operate unstably, thereby making it difficult to control the superheat through the superheat sensor 240.

The LSHX 230 may effectively boost the efficiency of the A/C system 200 by at least about 5% as compared to A/C system 100. However, in some embodiments, the LSHX 230 may provide an increase in efficiency of at least about 10% as compared to A/C system 100. For example, if A/C system 100 comprises a 25 Seasonal Energy Efficiency Ratio (SEER) rating, A/C system 200 may comprise a 27.5 Seasonal Energy Efficiency Ratio (SEER) rating. In part, the increase in efficiency may be attributed to the LSHX 230 providing at least about 5 degrees Fahrenheit less subcooling leaving the outdoor heat exchanger 118 (condenser) and/or at least about 10 degrees less superheat leaving the indoor heat exchanger 114 (evaporator) as compared to A/C system 100 while the subcooling entering the indoor metering device 112 and the superheat entering compressor 116 remain substantially the same. However, in some embodiments, the LSHX 230 may provide at least about 10 degrees Fahrenheit more subcooling and/or at least about 10 degrees more superheat as compared to A/C system 100. In other embodiments, the LSHX 230 may provide at least about 15 degrees Fahrenheit more subcooling and/or at least about 15 degrees more superheat as compared to A/C system 100.

It will be appreciated that although the LSHX 230 is depicted as being installed in an air conditioning (A/C) system 200, the LSHX 230 may also be configured to be installed in the indoor unit of a reversible heating, ventilation and/or air conditioning (HVAC) heat pump system. When the HVAC heat pump system is operated in a cooling mode, the LSHX 230 and/or the superheat sensor 240 would operate substantially similar to A/C system 200. However, it will be appreciated that the HVAC system may comprise a reversing valve installed in the outdoor unit 124 that is configured to reverse the flow of refrigerant through the HVAC heat pump system. Thus, when the HVAC heat pump system is operated in a heating mode, the flow of refrigerant through the HVAC heat pump system will be reversed as compared to the flow of refrigerant in the cooling mode. Accordingly, the HVAC heat pump system may comprise a plurality of check valves, solenoid valves, and/or any other suitable configuration of valves that would effectively remove the LSHX 230 from the fluid circuit during operation in the heating mode. As such, any configuration of electronic solenoids and/or electrically controlled valves may be controlled by the system controller 106, the indoor controller 124, and/or the outdoor controller 126 to remove the LSHX 230 from the fluid circuit. Additionally, the HVAC heat pump may also comprise a bypass line and/or a plurality of bypass lines that operate in conjunction with the valves to remove the LSHX 230 from the fluid circuit when the HVAC heat pump system is operated in the heating mode.

Referring now to FIG. 3, a flowchart of a method 300 of operating an A/C system 200 is shown according to an embodiment of the disclosure. The method 300 may begin at block 302 by providing an A/C system 200 comprising a Liquid/Suction Heat exchanger (LSHX) 230 in an indoor unit 202 of the A/C system 200. Generally, the LSHX 230 may be coupled between an outdoor heat exchanger, such as outdoor heat exchanger 118, and an indoor metering device, such as indoor metering device 112, on a so-called “liquid” line. Additionally, the LSHX 230 may be coupled between an indoor heat exchanger, such as indoor heat exchanger 108, and a compressor, such as compressor 116, on a so-called “vapor” line. The method 300 may continue at block 304 by operating the A/C system 200 in a cooling mode. The method may continue at block 306 by increasing the amount of subcooling in the refrigerant by passing the refrigerant through a liquid line of the LSHX 230. The method 300 may continue at block 308 by passing the higher subcooled refrigerant through an expansion device 112 and an indoor heat exchanger 108. The method may continue at block 310 by increasing the amount of superheat in the refrigerant by passing the refrigerant through a vapor line of the LSHX 230. The method may continue at block 312 by monitoring the amount of superheat in the higher superheated refrigerant exiting the LSHX 230. The method 300 may conclude at block 314 by controlling the position of the indoor metering device 112 in response to monitoring the amount of superheat in the higher superheated refrigerant exiting the LSHX 230 to control the amount of superheat in the refrigerant exiting the LSHX 230. In some embodiments, the temperature of the superheated refrigerant may be monitored via a superheat sensor 240 disposed downstream of the LSHX 230. In alternative embodiments, the temperature of the superheated refrigerant may be monitored via a superheat sensor 240 disposed upstream of the LSHX 230 and downstream from the indoor heat exchanger 108.

Referring now to FIG. 4, a schematic diagram of a general-purpose processing (e.g., electronic controller or computer) system 1300 is shown according to an embodiment of the disclosure. In some embodiments, processing system 1300 may be system controller 106, indoor controller 124, and/or outdoor controller 126 and be suitable for implementing one or more embodiments disclosed herein. In addition to the processor 1310 (which may be referred to as a central processor unit or CPU), the system 1300 may comprise network connectivity devices 1320, random access memory (RAM) 1330, read only memory (ROM) 1340, secondary storage 1350, and input/output (I/O) devices 1360. In some cases, some of these components may not be present or may be combined in various combinations with one another or with other components not shown. These components may be located in a single physical entity or in more than one physical entity. Any actions described herein as being taken by the processor 1310 might be taken by the processor 1310 alone or by the processor 1310 in conjunction with one or more components of the processor system 1300.

The processor 1310 generally executes algorithms, instructions, codes, computer programs, and/or scripts that it might access from the network connectivity devices 1320, RAM 1330, ROM 1340, or secondary storage 1350 (which might include various disk-based systems such as hard disk, floppy disk, optical disk, or other drive). While only one processor 1310 is shown, processor system 1300 may comprise multiple processors 1310. Thus, while instructions may be discussed as being executed by a processor 1310, the instructions may be executed simultaneously, serially, or otherwise by one or multiple processors 1310. The processor 1310 may be implemented as one or more CPU chips.

The network connectivity devices 1320 may take the form of modems, modem banks, Ethernet devices, universal serial bus (USB) interface devices, serial interfaces, token ring devices, fiber distributed data interface (FDDI) devices, wireless local area network (WLAN) devices, radio transceiver devices such as code division multiple access (CDMA) devices, global system for mobile communications (GSM) radio transceiver devices, worldwide interoperability for microwave access (WiMAX) devices, Bluetooth, CAN (Controller Area Network) and/or other well-known technologies, protocols and standards for connecting to networks. These network connectivity devices 1320 may enable the processor 1310 to communicate with the Internet or one or more telecommunications networks or other networks from which the processor 1310 might receive information or to which the processor 1310 might output information.

The network connectivity devices 1320 might also include one or more transceiver components 1325 capable of transmitting and/or receiving data wirelessly in the form of electromagnetic waves, such as radio frequency signals or microwave frequency signals. Alternatively, the data may propagate in or on the surface of electrical conductors, in coaxial cables, in waveguides, in optical media such as optical fiber, or in other media. The transceiver component 1325 might include separate receiving and transmitting units or a single transceiver. Information transmitted or received by the transceiver component 1325 may include data that has been processed by the processor 1310 or instructions that are to be executed by processor 1310. Such information may be received from and outputted to a network in the form, for example, of a computer data baseband signal or signal embodied in a carrier wave. The data may be ordered according to different sequences as may be desirable for either processing or generating the data or transmitting or receiving the data. The baseband signal, the signal embedded in the carrier wave, or other types of signals currently used or hereafter developed may be referred to as the transmission medium and may be generated according to several methods well-known to one skilled in the art.

The RAM 1330 might be used to store volatile data and perhaps to store instructions that are executed by the processor 1310. The ROM 1340 is a non-volatile memory device that typically has a smaller memory capacity than the memory capacity of the secondary storage 1350. ROM 1340 might be used to store instructions and perhaps data that are read during execution of the instructions. Access to both RAM 1330 and ROM 1340 is typically faster than access to secondary storage 1350. The secondary storage 1350 is typically comprised of one or more disk drives or tape drives and might be used for non-volatile storage of data or as an over-flow data storage device if RAM 1330 is not large enough to hold all working data. Secondary storage 1350 may be used to store programs or instructions that are loaded into RAM 1330 when such programs are selected for execution or information is needed.

The I/O devices 1360 may include liquid crystal displays (LCDs), touch screen displays, keyboards, keypads, switches, dials, mice, track balls, voice recognizers, card readers, paper tape readers, printers, video monitors, transducers, sensors, or other well-known input or output devices. Also, the transceiver component 1325 might be considered to be a component of the I/O devices 1360 instead of or in addition to being a component of the network connectivity devices 1320. Some or all of the I/O devices 1360 may be substantially similar to various components disclosed herein.

At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R₁, and an upper limit, R_(u), is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R₁+k*(R_(u)−R₁), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Unless otherwise stated, the term “about” shall mean plus or minus 10 percent of the subsequent value. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present invention. 

What is claimed is:
 1. An indoor unit of an air conditioning (A/C) system, comprising: a liquid/suction heat exchanger (LSHX); and a superheat sensor configured to monitor the amount of superheat in refrigerant exiting the LSHX.
 2. The indoor unit of claim 1, further comprising: an indoor metering device configured to control the amount of superheat in the refrigerant exiting the LSHX in response to the superheat sensor monitoring the amount of superheat in the refrigerant exiting the LSHX.
 3. The indoor unit of claim 2, further comprising: an indoor metering device controller configured to control the position of the indoor metering device to control the amount of superheat in the refrigerant exiting the LSHX.
 4. The indoor unit of claim 1, wherein the LSHX is configured to increase an amount of subcooling in refrigerant received via a liquid line from an outdoor heat exchanger of an outdoor unit.
 5. The indoor unit of claim 1, wherein the LSHX is configured to increase an amount of superheat in refrigerant received from an indoor heat exchanger of the indoor unit.
 6. The indoor unit of claim 1, wherein the LSHX is configured to prevent liquid-phase refrigerant from entering a compressor of the outdoor unit.
 7. A heating, ventilation, and/or air condition (A/C) system, comprising: an outdoor unit; and an indoor unit, comprising: a liquid/suction heat exchanger (LSHX); and a superheat sensor configured to monitor the amount of superheat in refrigerant exiting the LSHX.
 8. The A/C system of claim 7, wherein the indoor unit comprises an indoor metering device configured to control the amount of superheat in the refrigerant exiting the LSHX in response to the superheat sensor monitoring the amount of superheat in the refrigerant exiting the LSHX.
 9. The A/C system of claim 8, wherein the indoor unit comprises an indoor metering device controller configured to control the position of the indoor metering device to control the amount of superheat in the refrigerant exiting the LSHX.
 10. The A/C system of claim 7, wherein the LSHX is coupled between an outdoor heat exchanger of the outdoor unit and an indoor metering device of the indoor unit via a liquid line of the LSHX.
 11. The A/C system of claim 10, wherein the LSHX is configured to receive subcooled refrigerant from the heat exchanger of the outdoor unit through the liquid line.
 12. The A/C system of claim 11, wherein the LSHX is configured to increase the amount of subcooling in the refrigerant received from the heat exchanger of the outdoor unit through the liquid line.
 13. The A/C system of claim 12, wherein the LSHX is configured to increase the amount of subcooling in the refrigerant by at least about 5 degrees Fahrenheit.
 14. The A/C system of claim 7, wherein the LSHX is coupled between an indoor heat exchanger of the indoor unit and a compressor of the outdoor unit via a vapor line of the LSHX.
 15. The A/C system of claim 14, wherein the LSHX is configured to receive superheated refrigerant from the indoor heat exchanger of the indoor unit through the vapor line.
 16. The A/C system of claim 15, wherein the LSHX is configured to increase the amount of superheat in the refrigerant received from the indoor heat exchanger of the indoor unit through the vapor line.
 17. The A/C system of claim 16, wherein the LSHX is configured to prevent liquid-phase refrigerant from entering the compressor of the outdoor unit.
 18. The A/C system of claim 7, wherein the A/C system comprises a reversible heating, ventilation, and/or air conditioning (HVAC) heat pump system.
 19. A method of operating a heating, ventilation, and/or air condition (A/C) system, comprising: providing an A/C system comprising an outdoor unit and an indoor unit comprising an indoor metering device and a liquid/suction heat exchanger (LSHX); operating the A/C system in a cooling mode; monitoring the amount of superheat in refrigerant exiting the LSHX; and controlling a position of the indoor metering device to control the amount of superheat in the refrigerant exiting the LSHX.
 20. The method of claim 19, further comprising: increasing the amount of subcooling in the refrigerant by passing the refrigerant through a liquid line of the LSHX; and increasing the amount of superheat in the refrigerant by passing the refrigerant through a vapor line of the LSHX. 